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The paper describes the development of methanol fueled engines for passenger cars and light duty trucks working both on the compression ignition and glow plug assisted ignition principle. Special emphasis was laid on development and optimization of the combustion process for both the glow plug assisted and the compression ignition system, the application of the engine management system and the development of the exhaust after-treatment under steady state conditions on the engine dynamometer. The transient engine development in the test car was carried out on chassis dynamometer and under road conditions. The glow plug assisted direct injection methanol engine was in addition equipped with oxidation catalysts for this development program.

Research and development activities on high-performance S.I. engines for passenger car application are mainly concentrated on full load performance development as well as the development of combustion systems and engine structures in order to meet future market and legislation requirements. This paper presents results out of AVL's R&D work in the field of multi-valve S.I. engines. Variable Intake Systems of different design are compared to Variable Valve Timing devices with respect to overall engine performance. Engine and vehicle test results of a four-valve engine with the AVL developed C̱ontrolled Ḇurn Ṟate (CBR) combustion system are presented and analyzed. The control of charge stratification, charge motion and hence of the combustion pattern turns out as a major requirement for the investigated advanced combustion systems.

Based on the results of intensive research work on S.I. engines, AVL has developed combustion systems responsive to both the requirements of expected limitations in worldwide energy supply and to current and future exhaust emission standards. Supported by single-cylinder research work on two-valve and four-valve combustion systems for the combustion of lean and diluted charges, multi-cylinder engine development work and vehicle testing has been carried out. The results of this development work demonstrate the potential of AVL High Compression Fast Burn (HCFB) Combustion Systems with regard to fuel economy “and exhaust emissions unser ECE and US-Federal test conditions.

AVL's research work on advanced combustion systems for four-stroke gasoline engines has revealed a strong influence of charge motion and mixture preparation on engine performance, especially exhaust emissions and fuel economy. This paper presents the effects of mixture preparation and charge motion revealed in studies of AVL High Compression Fast Burn (HCFB) combustion systems. Major combustion parameters were investigated and optimized. Control of charge stratification emerged as one of the key elements of advanced combustion systems for both two-valve and four-valve engine configurations. Consequently, measures for charge stratification control are also presented.

AVL's research program on highly fuel efficient low emission two-stroke engines initiated the development of an advanced cycle simulation program to optimize the intake and exhaust systems and the port timing, as well as the investigation of various fuel or mixture injection systems. The current paper covers the application of the engine simulation program to multi-cylinder engines and presents a summary of the latest test results with the AVL-Direct Mixture Injection System on a 250cc single-cylinder research engine. An analysis of the gas dynamics in the exhaust system of a crankcase scavenged automotive three-cylinder engine is presented and the influence of important dimensions of the exhaust manifold on the pressure wave propagation and on the torque characteristic of the engine is discussed in detail.

AVL's development of a semi-direct injected two-stroke engine employed a carburetted 250cc production motorcycle engine as a baseline. Special emphasis vas placed on the investigation of fuel jet and scavenge flow interactions. To evaluate the scavenge flow pattern, a steady flow test procedure was developed and applied. The results of scavenging system optimization were confirmed by subsequent engine tests which showed significant gains in power output. Completion of the first phase of the research program resulted in the development of a semi-direct injection system using currently available automotive low pressure manifold injection system components. Compared to the original carburetted engine, significant improvanents were demonstrated, including a 30% reduction of fuel consumption, a reduction of up to 60% in hydrocarbon emissions and up to 70% in carbon monoxide emission, averaged over the engine's speed and load range.

The market-driven need to further improve the fuel economy of passenger cars, while meeting current and anticipated future emission regulations, represents a challenging target for today's engine research and engineering. Based on the results of intensive spark ignited engine combustion system research work. AVL has developed a development strategy that is responsive to both the require-rents of expected limitations in worldwide energy supply and to current and proposed exhaust emission standards. This strategy is presented in this paper. Supported by single cylinder research engine investigations into the combustion phenomena of lean homogeneous mixtures, multi-cylinder engine development has been carried out on two in-line (IL) four cylinder engines, of 1.6 and 2.3 litre displacement, respectively.